2025 – PAGE 212 – EMERGENCY MEDICINE & TOXICOLOGY
CLONIDINE & PHENOTHIAZINES OVERDOSE
Overdose from clonidine and phenothiazines typically results in hypotension but may cause transient or rebound hypertension. Both can cause miosis. Clonidine can also produce some anticholinergic effects (dry mouth, constipation, and CNS depression), cogwheel rigidity, and dystonic reactions.
- (DOUBLE TAKE) DYSTONIC REACTIONS: Dystonic reactions involve sudden muscle contractions and usually some odd postures. These can be related to clonidine, phenothiazine, metoclopramide, promethazine, and athetoid cerebral palsy. Treat medication-induced dystonic reactions with diphenhydramine.
BETA BLOCKER OVERDOSE
A beta blocker overdose may cause bradycardia and hypotension. Severe toxicity may lead to arrythmias, seizure, hypoglycemia, and bronchospasm. Give charcoal for recent ingestion, IV atropine for symptomatic bradycardia, IV glucagon to increase heart rate and contractility, high-dose insulin with glucose if glucagon is ineffective, and give IV calcium gluconate or calcium chloride for myocardial support. Use vasopressors like epinephrine or norepinephrine for persistent hypotension.
CALCIUM CHANNEL BLOCKER OVERDOSE
Calcium channel blocker overdose results in hypotension. Treat with CALCIUM to “unblock” the blocker effect!
DIGOXIN TOXICITY
Digoxin toxicity leads to anorexia, weakness, nausea and vomiting, poor appetite, and almost any kind of cardiac arrhythmia. There is an increased chance of digoxin toxicity if there is LOW K+, LOW Mg, poor renal function, or hypoxia. Monitor the EKG. Treat with activated charcoal for a recent ingestion, or Digibind if the toxicity is life-threatening, and correct any hypokalemia and hypomagnesemia. Management of arrhythmias depends on the type.
THEOPHYLLINE
At theophylline levels > 20, nausea, vomiting, hypOtension, HYPERcalcemia, HYPOkalemia, metabolic acidosis, and seizures will occur. Treat with CHARCOAL until the level normalizes, and give beta-blockers for arrhythmias (if the blood pressure is not too low). Use benzodiazepines for seizures. You may also choose to do emergent hemodialysis or whole bowel irrigation if levels continue to increase.
PEARL: Multiple and late doses of charcoal are allowed because of increased GI transit time (due to decreased motility) and charcoal’s systemic absorption of theophylline.
CARBON MONOXIDE (CO)
Carbon monoxide (CO) can cause ERYTHEMATOUS/FLUSHED skin, flu-like symptoms, ATAXIA, confusion, lethargy, somnolence, GI symptoms, and headache. It can be associated with burns/fires. The CO reversibly binds to hemoglobin, creating carboxyhemoglobin (obtain a level). Treat with 100% O2 if mild. If the carboxyhemoglobin level is > 25%, the patient has GI symptoms or the patient has neurologic symptoms, then treat with 100% O2 in a hyperbaric chamber.
PEARLS: Pulse oximetry may read as NORMAL (don’t let them trick you!). If you see 100% O2 as an answer choice, consider this as the etiology. The patients may present as a drunken-appearing family, or a family with a prolonged viral syndrome. Presentation is similar to cyanide poisoning. If the patient is not getting better on 100% O2, go ahead and treat for cyanide poisoning with Sodium Thiosulfate or Nitrate.
MNEMONIC: If you’ve ever had a CO monitor, it was probably located where it is HOT AS HECK! For example, maybe it was in the basement laundry room where your skin is already HOT, RED, and FLUSHED!